PROJECT SUMMARY/ABSTRACT A major roadblock in regenerative medicine is the ability to resolve disease-associated inflammation and to optimize tissue regenerative capacity to prevent further tissue destruction secondary to inflammation or scarring. Recently, a major breakthrough in mesenchymal stem cells (MSCs) research identifies an intrinsic role of MSCs in immune-regulatory function. We have demonstrated that pro-inflammatory cytokines are required for immunosuppressive function of MSCs through the concerted action of chemokines, and nitric oxide, and that activated T cells can induce apoptosis of MSCs via the Fas/Fas L pathway. Our studies also have revealed that the immunosuppressive property of skin derived MSCs were tightly regulated by the local inflammatory niche mediated by the autocrine/paracrine IL17/IL6 axis, and therapeutic approaches targeting these distinct niche components resulted in suppression of excessive scar formation. Based on these observations, we explore the feasibility of isolating MSCs from human gingiva (hGMSCs), a unique oral tissue that functions both as a biological mucosal barrier and a component of the oral mucosal immunity. Interestingly, hGMSCs exhibit not only multipotent differentiation and self-renewal capacities but also possess superior immunosuppressive effect as compared to bone marrow mesenchymal stem cells (BMMSC), by inducing Tregs expansion and inhibiting Th17 cells, and consequently, suppress tissue destruction in our inflammation-related tissue injury/osteonecrosis model induced by bisphosphonate (BRONJ). We hypothesize that GMSCs are capable of playing dual roles in tissue repair including a protective role as an immunomodulator to inhibit tissue injury and a tissue regeneration role through their multipotent differentiation capacities. In this application, our interdisciplinary team with advanced specialties in stem cell biology, immunology, tissue repair/regeneration, and clinical therapies, proposes to elucidate the molecular mechanisms of inflammation- related tissue injury/degeneration, and develop a novel therapeutic approach using GMSCs to suppress inflammation and promote regeneration/reconstruction of diseased and injured oral and craniofacial tissues. Our objective will be addressed using three integrated specific aims: 1) To further delineate stem cell properties of hGMSCs at the single colony level; 2) To determine whether hGMSCs are capable of immunomodulation and the underlying mechanisms; and 3) To explore the feasibility of targeting GMSCs to reduce inflammation and promote tissue regeneration in animal models of inflammation- related oral disorders/diseases. This study will substantially extend current knowledge of the immunomodulatory functions of GMSCs and provide critical pre-clinical data to test the feasibility and efficacy of novel therapeutic approach using GMSC to harness inflammation and enhance regeneration of inflammation-related or injured orofacial tissues.